Marbury last night turned down an offer to be installed as the Knicks’ starting shooting guard for the rest of the season, according to two team sources.

Down to just two guards following trades, an injury to Nate Robinson and Cuttino Mobley’s ongoing heart tests, coach Mike D’Antoni talked with Marbury at their Detroit hotel before last night’s game at The Palace against the Pistons, telling Marbury he wanted him to join the fray – the second time in a week D’Antoni has asked Marbury to play.

This time, D’Antoni told Marbury it would be permanent, not just a one-night stand, according to the two sources. But Marbury stuck to his guns. He said the team had decided to go in a different direction and the damage was too significant to repair, with buy-out talks having already begun, according to the two sources.

The latest episode could draw the ire of Knicks president Donnie Walsh and lead to disciplinary action. It was a shocking reversal for D’Antoni to attempt to resurrect Marbury. D’Antoni did not want Marbury to attend training camp and even told him on Friday he was surprised to see him in Saratoga Springs.

So far, Walsh has not viewed Marbury’s behavior stemming from Friday’s incident in Milwaukee as insubordination when he declined a chance to play.

However, a source said this time Walsh is considering investigating the matter as a contract violation, according to the sources, and fine him a game’s pay. Marbury is to make $21.9 million this season, and a game’s pay ($199,091) is considered 1/110th the wage.

D’Antoni’s changing course on Marbury stemmed from last week’s trades of Jamal Crawford and Mardy Collins, Robinson’s groin injury and the Mobley crisis. Mobley, who is still undergoing tests, has a heart issue that could jeopardize his season.

D’Antoni, according to a source, also was emboldened because Marbury had two strong practices since returning to scrimmaging.

Marbury, who has yet to play a minute this season, had a different version of yesterday’s events. He said D’Antoni and he had talked in the afternoon about playing but he wasn’t specific.

“If they want to play me, they can play me,” said Marbury, who did not ride the team bus. “If they don’t want to play me, that’s fine.”

D’Antoni, according to the two sources, was angrier yesterday than after Friday’s incident, feeling there could be no misinterpretation of his wishes. The sources said D’Antoni purposely made it clear he wanted to give Marbury a crack at a starting backcourt position in the wake of the giant roster reshuffling across the past six days. Privately, Marbury has talked about playing shooting guard with his next club.

D’Antoni last night declined to be specific, only to say Marbury would not dress.

“Status quo. It hasn’t changed any from the last time,” D’Antoni said. “I just don’t want to keep talking about it. We’ll follow the same path and we’ll go from there.”

Asked if he thought Marbury would be out of shape from not playing, D’Antoni said, “I would think he’s ready. He’s practiced. I don’t see why he wouldn’t.”

Chris Duhon and journeyman Anthony Roberson were the only healthy guards available last night. Quentin Richardson moved from small forward to starting shooting guard last night and ripped Marbury afterward.

On Friday in Milwaukee, D’Antoni asked Marbury if he wanted to play, and the Knick lightning-rod guard indicated he would rather not. Marbury disputed that he refused to play in Milwaukee, telling The Post he taped his ankles ready for action if needed.

Currently, the Knicks are wasting a roster spot with Marbury and likely will be forced to reach a resolution quickly. Patrick Ewing Jr., a small forward whom they are interested in re-signing, has attended several games, works out at their practice facility and is seen often in the locker room.

Mobley was slated to take Crawford’s slot at shooting guard. But Walsh would not guarantee if Mobley will play this season.